Cheese sauce problems - need help!

In the last few months, I've completely lost the ability to make my favorite mac n' cheese recipe. The recipe is nothing fancy, but I've listed it below for troubleshooting purposes. This is for 3 C uncooked macaroni (cooked according to the package).

My recent problem has been that when I add the cheese - slowly, stirring, like a good little cook! - it lumps up, and I end up with globs of stringy melted cheese amidst my noodles-in-milk. The only thing I can think of is that I used to use fontina instead of Swiss (as per the recipe!) but lately we've had Swiss on hand so I've used that instead. Could that be the problem? Any other ideas? I am getting very sad...

You mention using Fontina in place of Swiss; then you say "lately we've had Swiss on hand so I've used that instead". Does that mean that the problem went away with your return to Swiss? From your description, the only thing that comes to my mind is that your roux may too hot when you introduce the cheese (cheese should never be allowed to reach boiling temperatures when preparing sauces. I also assume you are shredding the cheese before introducing it, a little at a time (let first handful melt before adding the next)

Thanks - these are good tips. The white sauce may have been too hot; I'll let it cool before my next attempt. And it sounds like the Swiss (the more recent addition) may be the culprit... we'll ditch that and go for Fontina instead, along with home-grated cheddar.

I always start with a bechamel instead of the way you're making white sauce -- grated cheese always seems to combine well when I use that method. So here you go, in case you want to try something slightly different:

Melt 2 T. butter in a saucepan, add 2 T. flour, and cook over low heat for about 2 minutes, enough time to cook out the floury taste but not to brown it. Then, while whisking, slowly pour in 1 1/2 C. milk, whisking after each addition until fully incorporated. Bring up to a boil, then turn to med-low, and whisk until thickened.

You can put the grated cheese into this sauce right when you take it off the heat. Also add salt and pepper to taste at this point, and a little cayenne pepper if you want the added kick.

Of course, the recipe can be doubled if you want more sauce for your macaroni. Just use a saucepan that's big enough, so the milk doesn't boil over and go everywhere. Yes, this has happened to me.

There is a process you must follow. First, you must have an adequate amount of roux (butter *and* flour, not just flour) to the amount of milk. The stability and thickness of your sauce will be depend on this proportion. For a thin sauce it is usually one tablespoon *each* of flour and butter to every cup of milk; for a thicker sauce it will be two tablespoons each. You cook the butter and flour together on medium-low heat for about five minutes, until the looks an ivory color (what chefs call blond) and smells nutty when you get close. This also prevents lumps. Your goal is to get the fat and the starch in the flour to link up on a molecular level -- and that takes more than a minute or two.

Then you can whisk in a single ladle of already heated milk (that you have in a separate saucepan near). Once that is incorporated and the mixture thickens, gradually (meaning, ladle by ladle) add the rest of the milk. Keep whisking and the mixture will thicken and become glossy. Remember, you cannot add all the milk at once or you overwhelm the mixture and defeat your purpose.

Once all the milk has been added, reduce heat to low and cook the mixture for 5-7 minutes, whisking frequently, to give the starch molecules the time to grab onto all that liquid and hold it securely -- and when it's thick and glossy and absolutely smooth -- take the white sauce off the heat, and it will be happy to incorporate your grated cheese handful by handful. It's chemistry. You have to have the right proportions, and you can't rush the process.

The addition of a teeny amount of Colman's Hot Mustard (this is a powder) will add both flavor and kick, as well as act as an emulsifier so your sauce doesn't become grainy. It will be very creamy. You have to make enough, of course, to coat your macaroni, with a little extra to put on the top. I like to finish the mac ‘n’ cheese under the broiler for 2-3 minutes.